Electroresponsive device



E. H. BANCKER 2,110,655

March 8, 1938.

ELECTRORESPONS IVE DEVI CE Filed Nov. 21, 1936 Invent or: E I bevt H. Bancher;

9 His Attorney.

Patented Mar. 8, 1938 v UNITED STATES PATENT OFFICE ELECTRORESPONSIVE DEVICE Elbert H. Bancker, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application November 21, 1936, Serial No. 112,069 3 Claims. (Cl. 175-494) My invention relates to improvements in electhe movable current conducting member may troresponsive devices and more particularly to arise from other conditions, which result, for eximprovements in protective relays for polyphase ample, from certain winding arrangements and alternating current electric systems. My invenalso from manufacturing limitations, it is very 5 tion in general relates to improvements in elecdesirable to be able to eliminate such unwanted 5 troresponsive devices such as are disclosed and efiects. claimed in the copending application of V. E. Ver- In accordance with my invention, I provide an rall, Serial No. 70,580, filed March 24, 1936, for improved electroresponsive device which is com- Electroresponsive device, and assigned to the pact and simple in construction and which is same assignee as this invention, and more parefficient and fast in operation. Furthermore, in 10 ticularly to improvements in electroresponsive accordance with my invention, I provide an elecdevices such'as are disclosed in the copending troresponsive device wherein suitable return application of D. C. Prince, Serial No. 112,067, paths are provided for the residual fluxes so as filed Nov. 21, 1936, for Electroresponsivedevice, to eliminate undesired actions and to effect the and assigned to the same assignee as this invendesired response of the device. These and other 15 tion. An object of my invention is to provide an objects of my invention will appear in more deimproved electroresponsive device which responds tail hereinafter.

to a predetermined function of a group of coex- My invention will be better understood from isting polyphase quantities without interference the following description when taken in connec- 0 from certain undesired efiects which may arise tion with the accompanying sheet of drawings,

under some conditions. and its scope will be pointed out in the appended In the Verrall application, there is disclosed a claims. construction wherein the actuation of a single ro- In the accompanying sheet of drawings, Fig.

tor is controlled by windings on the radially dis- 1 is a plan view partially in section" and partially posed salients of a magnetic member. There is broken away illustrating an electroresponsive de- 25 also further disclosed a polyphase relay which vice embodying my invention; Fig. 2 is a sectional comprises a plurality of these units. elevation on the line 22 of Fig. 1 as seen in a In the Prince application there is disclosed an single planeafter revolution of the diagonal secimprovement of the Verrall disclosure whereby tional part of Fig. 1; Figs. 3, 4, and 5 are diaa single unit device can be made to respond to a grammatic views of devices analogous to the de- 30 predetermined function of two groups of coexistvice shown in Figs." 1 and 2 for explanatory puring polyphase quantities. This construction proposes; and Fig. 6 is a diagrammatic illustration vides a very compact and eflicient device which showing the application of an embodiment of my meets the present day protective relay requireinvention illustrated in Figs. 1 and 2 to a polyments for high torque and speed. However, with phase circuit. 35 this arrangement, there may arise under certain The electroresponsive device illustrated in Figs. conditions an undesired action which interferes 1 and 2 is similar in construction to the electrowith the correctness of the desired response. For responsive device disclosed in the Verrall appliexample,- if the device is built to respond to a cation. As shown in Figs. 1 and 2, this device component of the polyphase power of the system comprises a hollow magnetic stator 15 having a 40 for operation on the occurrence of interphase plurality of inwardly projecting salients l5l-l68, faults, then on the occurrence of a ground fault inclusive. Certain of these salients, those on the there may result an undesired effect dependent sides, for example, may be integral with the upon the ground fault power because there is stator and the others insertable in the stator.

no suitable flux return path for the fluxes due to Windings I! are provided for energizing the 45' residual or zero phase sequence component quansalients and also a central magnetic member l8 tities. Since, in some cases, the action due to concentrically positioned with respect to the ends this residual flux entering the movable current of the salients whereby to actuate a rotor l9, conducting member may be undesired, as stated which is movable in the gaps between the salients above, and in other cases may be desired to proand the stator Hi, the rotor being secured to a 50 duce a maximum eiiect where. for example, an suitably journaled shaft 20. .The parts described effective ground fault response is desired. it is are assembled as a unit between two end frames important that the effect of this residual flux be 2| and 22, which are held together by suitable controlled according to the form of protection means such as rivets 23. The stator 48 is prefr, desired. Inasmuch as residual fluxes entering erably of magnetic material and is mounted on a which are produced by the windings I1.

supporting member or hub 24. This hub is mounted in the bottom frame member 2!, as

shown. In accordance with my invention, I provide a definite return path for certain fluxes As disclosed, this path is in eiTect a shunt fiux path and may-be provided by having one of the frame members 2| which supports the stator l8 of suitable magnetic material and also the hub 24.

In Figs. 3, 4, and 5, which are intended as schematic representations of devices analogous to that shown in Figs. 1 and 2, similar reference numbers indicate corresponding parts. In the Prince application referred to herein, there is disclosed a device having six salients, lBl-llfifi, inclusive, energized by a set of three-phase quantities I, 2, 3 in the order l, 2, 2, l, 3, 3, as indicated by the numbers at the ends of the respective windings ll. Then the rotating field produced by the windings on the salients ltl, its, and N55 is opposite in torque efiect to the rotating field produced by the windings ll on the salients M52, M 3, M56. Other things being equal, the resultant torque on the rotor 19 is zero. Also as disclosed in the Prince application, this action can be obtained with a simplified stator l5 having only four salients for a three-phase system of electric quantities, as shown in Fig. 4, or, in general, 2(71-1) salients for an n-phase system. Thus, if the windings H are energized by three phase quantities, as for example, the phase currents of a three-phase system, in the cyclic order l, 2, 3, 2, as indicated by the numbers at the ends or" the respective windings, then the torque of the rotating field produced by the windings H on the salients lfil, M53, M55 is opposite to the torque of the rotating field produced, on the stator by the salients [It i tel, ltli. Other things being equal, the resultant torque is zero and the rotor it! is not actuated/ Ihejwindings ll may be energized by a set ofthree'phasefloltages in a similar order-and'theresultant torque on the rotor would benothing. If, however, it is desired to obtain a torque which is dependent, for eX- aniplei on the sum of the products of the cur- W ts and the voltages of a polyphase system and ve'suchtorque independent-attire terms of ne second order involving only cur rent or voltage then, as pointed out in the Prince application, alternate salients may-be energized by the currentslin the three phase conductors of a three- "phase system in the cyclic. order I1, I2, 13, I2, 'for example, and the windings ll on the intermediate salients by three phase voltages of the system in theforder E1, E2, E1, E3, as indicated by these letters at the ends of the windings. In this way,

the maximum torque is proportional to to the same assignee as this invention. As illustrated, the three-phase system comprises a threephase circuit whose phase conductors, designated l, 2, 3 for simplicity in phase order, may comprise a feeder connected to a station bus 30 through a circuit breaker 33 having a trip coil 34, the respective phase currents may be derived from current transformers 3|, and the voltages through a potential transformer 32 connected to the bus 30, a further Y-open delta potential transformer 320 may be connected to be energized from the bus 30 through the transformer 32 in order to provide zero phase sequence voltage in case of ground faults. In the schematic representation of the device in Fig. 6, the salient windings are indicated by the salient numbers, for simplicity. The relay device is shown as having a circuit controlling member 35 which is arranged to control contacts in circuit with the trip coil 34 whereby to control the opening of the circuit breaker 33.

As shown in Fig. 6, the salients IGI, I65, I66, and i168 are energized respectively by the currents I1, I2, and the phase voltages E12 and E23. The fluxes in these salients co-operate to pro duce a polyphase power directional torque. The windings on the salients Hi2 and H54 are connected in the open delta of the transformer 320] so as to be energized by the residual or zero phase sequence voltage of the system. The polarity of the connection of the winding on the salient N2 is reversed relatively to the polarity of the connection of the winding on the salient N54. The winding on the salient I163 is connected to be energized by the residual current of the circuit and for this purpose is connected to the residual lead of the current transformers 3l.'

The windings on the salients W62, M3, E54 accordingly provide the fluxes which produce a ground directional torque dependent on the flow of ground fault power. The salient Hill is energized by the phase voltage E31 reversed in polarity. The windings on the salients Hi6, Hill, and 268 provide a voltage restraint torque which is opposed to the power directional torque under predetermined system conditions. Such a relay, as shown in Figs. 13 and 2, when connected as shown in Fig. 6, then combines in a single device a response to polyphase power with a predetermined voltage restraint and to zero sequence power flow.

It will be observed, however, that with an arrangement such as is shown in Fig. 6 certain salients, via, M32, M53, and i6 1, are connected to be energized by zero phase sequence quantities and accordingly the fluxes in these salients would tend to pass through stator 58 and returnto the magnetic member 55 by way of the other salients. Such return fluxes would tend to establish miscellaneous torque efiects on the rotor it by virtue of their reaction withthe fluxes in the other poles. Such miscellaneous torque effects obviously decrease the effective accuracy 01 the device in its int nded response. For example, torque nd would be measured by and not by miscelequence quan" volt rion of a ground. fault would be the zero titles without the necessity for these fluxes entering other salients, which brings about the tendency to erroneous action. Thus, for example, the zero phase flux of the current energized salient I63 may pass directly into the stator l8 and thence into the magnetic hub supporting this stator and from there into the magnetic end frame 2| and thence back to the magnetic member IS without interacting with other salients to produce what may be termed mongrel torque effects.

While Fig. 6 shows one particular arrangement wherein my invention is effective in eliminating extraneous torque efiects, my invention is of course not limited to this particular application, since there are many cases where residual fluxes may arise and tend to affect the proper responsiveness of the device. For example, in manufacturing processes, it is seldom commercially possible to achieve the theoretically perfect design. In other words, there is a divergence between theory and practice dependent upon commercial limitations in manufacturing. Thus, even though none of the windings of the device were connected to be energized by zero phase sequence quantities of a circuit, there may be an actual residual flux even though the windings are connected in a balanced three-phase circuit because of a slight difference in the windings as to turn numbers, turn spacing, insulation, mounting on the salients, lack of symmetry in the magnetic member or the parts associated therewith, etc. However, if a shunt magnetic path is provided in accordance with my invention, these residual fluxes are rendered harmless in their deleterious effects upon the responsiveness of the device.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electroresponsive device comprising a magnetic stator in the form of a hollow square, said stator having a 'pluralityof inwardly projecting salients, a magnetic member centrally positioned relatively to and spaced from the inner ends of said salients, a rotor of electric current conducting material between said central magnetic member and the inner ends of said salients, windings for energizing said salients, and means for establishing a shunt magnetic path for the residual flux of said windings entering said rotor.

2. An electroresponsive device comprising a magnetic member having a plurality of radially disposed salients, a rotor having an electric current conducting path concentrically positioned relatively to the ends of said salients, energizing windings on said salients, and means for establishing a shunt flux path for the residual flux of said salients entering said conducting path.

3. An electroresponsive device comprising a hollow magnetic stator having a plurality of inwardly projecting salients, windings for energizing said salients, an end frame on each face of said stator, one of said end frames being of magnetic material, means for fastening together the end frames and stator, a central magnetic member supported by the magnetic end frame and centrally positioned relatively to and spaced from the inner ends of said salients and a rotatably mounted cylindrical member of electric current conducting material movable in the gaps between said central magnetic member and the inner ends of said salients.

4. An electroresponsive device comprising a magnetic stator having a plurality of radially disposed salients, energizing windings on said salients, a magnetic supporting member abutting said stator in the plane of said salients, a central magnetic member supported by said supporting member and centrally positioned relatively to and spaced from the inner ends of said salients, and a rotor having an electric current conducting p th mounted for rotation in the gaps between s id central magnetic member and the inner ends of said salients.

5. An electroresponsive device comprising a magnetic member having a plurality of radially disposed salients, a rotor having an electric current conducting path concentrically positioned relatively to the ends of said salients, energizing windings. on said salients, and frames constituting an enclosure for said magnetic member, rotor and windings, one of said frames being of magnetic material and means including said magnetic end frame for establishing a return flux path for any residual flux of said windings entering said current-conducting path.

6. An electroresponsive device comprising a single movable member having an electric current conducting path, and means for controlling the movement of said member in accordance with the magnitudes and phase displacements between predetermined electric quantities of two groups of coexisting polyphase quantities, including a magnetic member having a plurality of salients, windings on said salients and means for establishing a return flux path for any residual flux of said windings entering said current conducting path.

7. An electroresponsive device comprising a magnetic member having .a plurality of salients, a movable member having an electric current conducting path disposed adjacent the ends of said salients, energizing windings on certain of said salients, and means for establishing a shunt flux path for the residual fiux of said salients entering said current conducting path.

8. An electroresponsive device comprising a magnetic stator having a plurality of salients, a cooperating magnetic stator disposed adjacent the ends of said salients, energizing windings on certain of said salients, a magnetic member providing a return flux path between said stators, and a rotor having an electric current conducting path mounted for movement between said stators.

ELBERT H. BANCKER. 

